Ongoing Fen–Bog Transition in a Boreal Aapa Mire Inferred from Repeated Field Sampling, Aerial Images, and Landsat Data

Kolari, Tiina H. M.; Sallinen, Antti; Wolff, Franziska; Kumpula, Timo; Tolonen, Kimmo; Tahvanainen, Teemu

doi:10.1007/s10021-021-00708-7

Cited by 28 publications

(24 citation statements)

References 109 publications

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“…One mechanism of FBT, as recently recognized in several Finnish aapa mires, is a lateral expansion of Sphagnum ‐dominated bog margins over central fens (Granlund et al, 2022 ; Kolari et al, 2022 ). This phenomenon differs from the lateral expansion of mire vegetation over surrounding dry mineral soil, i.e., paludification (Bauer et al, 2003 ; Kuhry & Turunen, 2006 ), and it can rather be considered as a type of hydroseral development, initiating as infilling of flarks by floating Sphagna and eventually leading to terrestrialization as bog ecosystem (Granlund et al, 2022 ). This process in aapa mire complexes likely differs from the mid‐Holocene FBTs where transitional stages have often been associated with relatively dry poor‐fen vegetation with Eriophorum vaginatum (Hughes & Barber, 2003 ; Hughes & Dumayne‐Peaty, 2002 ; Tuittila et al, 2007 ; Väliranta et al, 2017 ).…”

Section: Introductionmentioning

confidence: 94%

“…In high‐latitude mires (peat‐accumulating wetlands), rising temperatures and lengthening of the growing season enhance gross primary production and promote the growth of decay‐resistant peat mosses ( Sphagnum spp. ; Charman et al, 2013 ; Gallego‐Sala et al, 2018 ; Kolari et al, 2021 ; Loisel et al, 2012 ; Ma et al, 2022 ), which can lead to an ecosystem‐level change from sedge‐dominated fens to Sphagnum ‐dominated bogs (Kolari et al, 2022 ; Loisel & Yu, 2013 ; Magnan et al, 2022 ; Tahvanainen, 2011 ). The fen‐bog transition (FBT) can alter the climate feedback of mires by increasing carbon sequestration (Granlund et al, 2022 ; Loisel & Yu, 2013 ) and by reducing methane emission (Juottonen et al, 2022 ; Zhang et al, 2021 ), while it poses threat to the biodiversity of fen habitats.…”

Section: Introductionmentioning

confidence: 99%

“…; Charman et al, 2013 ; Gallego‐Sala et al, 2018 ; Kolari et al, 2021 ; Loisel et al, 2012 ; Ma et al, 2022 ), which can lead to an ecosystem‐level change from sedge‐dominated fens to Sphagnum ‐dominated bogs (Kolari et al, 2022 ; Loisel & Yu, 2013 ; Magnan et al, 2022 ; Tahvanainen, 2011 ). The fen‐bog transition (FBT) can alter the climate feedback of mires by increasing carbon sequestration (Granlund et al, 2022 ; Loisel & Yu, 2013 ) and by reducing methane emission (Juottonen et al, 2022 ; Zhang et al, 2021 ), while it poses threat to the biodiversity of fen habitats. Recently, many studies of high‐boreal and subarctic peatlands have indicated increased carbon sequestration and FBT with warming after the Little Ice Age (LIA) and during the 20th century (Granlund et al, 2022 ; Loisel & Yu, 2013 ; Magnan et al, 2018 , 2022 ; Piilo et al, 2019 ; Primeau & Garneau, 2021 ; Robitaille et al, 2021 ).…”

Section: Introductionmentioning

confidence: 99%

“…The fen‐bog transition (FBT) can alter the climate feedback of mires by increasing carbon sequestration (Granlund et al, 2022 ; Loisel & Yu, 2013 ) and by reducing methane emission (Juottonen et al, 2022 ; Zhang et al, 2021 ), while it poses threat to the biodiversity of fen habitats. Recently, many studies of high‐boreal and subarctic peatlands have indicated increased carbon sequestration and FBT with warming after the Little Ice Age (LIA) and during the 20th century (Granlund et al, 2022 ; Loisel & Yu, 2013 ; Magnan et al, 2018 , 2022 ; Piilo et al, 2019 ; Primeau & Garneau, 2021 ; Robitaille et al, 2021 ). The FBT is well‐known from peat stratigraphies: Sphagnum peat in bogs is most often underlain by sedge peat of earlier fen phases, and the transition tends to be relatively short in duration (Hughes & Barber, 2003 ; Kuhry et al, 1993 ; Tuittila et al, 2013 ) and connected to a shift from high to low pH (Gorham & Janssens, 1992 ).…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, the FBT in this case connects to climate warming and the climate zonation of the focal mire types, as the expanding bog vegetation represents a southern element. Warming‐related changes can onset FBT in boreal mires (Kolari et al, 2022 ; Tahvanainen, 2011 ), providing one potential mechanism to explain the increase of carbon sequestration in northern mires, as projected for recent past and future (Gallego‐Sala et al, 2018 ).…”

Section: Introductionmentioning

confidence: 99%

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Inference of future bog succession trajectory from spatial chronosequence of changing aapa mires

Kolari

Tahvanainen

2023

Ecology and Evolution

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Climate change‐driven vegetation changes can alter the ecosystem functions of northern peatlands. Several case studies have documented fen‐to‐bog transition (FBT) over recent decades, which can have major implications, as increased bog growth would likely cause cooling feedback. However, studies beyond individual cases are missing to infer if a common trajectory or many alternatives of FBT are in progress. We explored plant community and hydrology patterns during FBT of 23 boreal aapa mire complexes in Finland. We focused on mires where comparisons of historical (1940–1970) and new (2017–2019) aerial photographs indicated an expansion of Sphagnum‐dominated zones. Vegetation plot and water chemistry data were collected from string‐flark fens, transition zones with indications of Sphagnum increase, and bog zones; thus, in a chronosequence with a decadal time span. We ask, is there a common trajectory or many alternatives of FBT in progress, and what are the main characteristics (species and traits) of transitional plant communities? We found a pattern of fen‐bog transitions via an increase in Sphagnum sect. Cuspidata (mainly S. majus and S. balticum), indicating a consistently high water table. Indicators only of transitional communities were scarce (Sphagnum lindbergii), but FBT had apparently facilitated shallow‐rooted aerenchymatous vascular plants, especially Scheuchzeria palustris. Water pH consistently reflected the chronosequence with averages of 4.2, 3.9, and 3.8, from fen to transition and bog zones. Due to weak minerotrophy of string‐flark fens, species richness increased towards bogs, but succession led to reduced beta diversity and homogenization among bog sites. Decadal chronosequence suggested a future fen‐bog transition through a wet phase, instead of a drying trend. Transitional poor‐fen vegetation was characterized by the abundance of Sphagnum lindbergii, S. majus, and Scheuchzeria palustris. Sphagnum mosses likely benefit from longer growing seasons and consistently wet and acidic conditions of aapa mires.

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Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Inference of future bog succession trajectory from spatial chronosequence of changing aapa mires

Kolari

Tahvanainen

2023

Ecology and Evolution

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Quantifying wetness variability in aapa mires with Sentinel‐2: towards improved monitoring of an EU priority habitat

Jussila,

Heikkinen,

Anttila

et al. 2023

Remote Sens Ecol Conserv

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Aapa mires are waterlogged northern peatland ecosystems characterized by a patterned surface structure where water‐filled depressions (‘flarks’) alternate with drier hummock strings. As one of the EU Habitat Directive priority habitats, aapa mires are important for biodiversity and carbon cycling, harbouring several red‐listed species and supporting unique species communities. Due to their sensitivity to hydrological disturbances, reliable, up‐to‐date and systematic information on the hydrological condition and responses of mires is crucial and required for multiple purposes ranging from carbon exchange modelling to EU Habitats Directive reporting and conservation and ecosystem restoration planning. Here, we demonstrate the usability of Sentinel‐2 satellite data in a semi‐automatic cloud‐based approach to retrieve large‐scale information on aapa mire hydrological variability. Two satellite‐derived metrics, soil moisture index and the extent of water‐saturated surfaces based on pixel‐wise classification, are used to quantify monthly and interannual wetness variation between 2017 and 2020 across Natura 2000 aapa mires in Finland, including responses to the extreme drought of 2018. The results revealed high temporal variability in wetness, particularly in the southern parts of the aapa mire zone and generally in the late summer months interannually. Observations from the drought summer showed that one third of usually year‐round wet flark surfaces may be exposed to drying during climatic extremes. Responses varied between sites and regions, implicating the significance of environmental factors for drought resistance: some sites maintained high levels of moisture, whereas others lost wet surfaces completely. Our study provides the first comprehensive national‐level representation of seasonal and interannual wetness variability and drought‐sensitivity of pristine aapa mire sites. The approach and methods used here can be directly upscaled outside protected areas and to other EU countries. Thus, they provide a means for harmonized, systematic large‐scale monitoring of this priority habitat, as well as valuable information for other applications supporting peatland conservation and research.

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Detecting Spatial Patterns of Peatland Greenhouse Gas Sinks and Sources with Geospatial Environmental and Remote Sensing Data

Christiani,

Rana,

Räsänen

et al. 2024

Environmental Management

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Peatlands play a key role in the circulation of the main greenhouse gases (GHG) – methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O). Therefore, detecting the spatial pattern of GHG sinks and sources in peatlands is pivotal for guiding effective climate change mitigation in the land use sector. While geospatial environmental data, which provide detailed spatial information on ecosystems and land use, offer valuable insights into GHG sinks and sources, the potential of directly using remote sensing data from satellites remains largely unexplored. We predicted the spatial distribution of three major GHGs (CH4, CO2, and N2O) sinks and sources across Finland. Utilizing 143 field measurements, we compared the predictive capacity of three different data sets with MaxEnt machine-learning modeling: (1) geospatial environmental data including climate, topography and habitat variables, (2) remote sensing data (Sentinel-1 and Sentinel-2), and (3) a combination of both. The combined dataset yielded the highest accuracy with an average test area under the receiver operating characteristic curve (AUC) of 0.845 and AUC stability of 0.928. A slightly lower accuracy was achieved using only geospatial environmental data (test AUC 0.810, stability AUC 0.924). In contrast, using only remote sensing data resulted in reduced predictive accuracy (test AUC 0.763, stability AUC 0.927). Our results suggest that (1) reliable estimates of GHG sinks and sources cannot be produced with remote sensing data only and (2) integrating multiple data sources is recommended to achieve accurate and realistic predictions of GHG spatial patterns.

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Ongoing Fen–Bog Transition in a Boreal Aapa Mire Inferred from Repeated Field Sampling, Aerial Images, and Landsat Data

Cited by 28 publications

References 109 publications

Inference of future bog succession trajectory from spatial chronosequence of changing aapa mires

Inference of future bog succession trajectory from spatial chronosequence of changing aapa mires

Quantifying wetness variability in aapa mires with Sentinel‐2: towards improved monitoring of an EU priority habitat

Detecting Spatial Patterns of Peatland Greenhouse Gas Sinks and Sources with Geospatial Environmental and Remote Sensing Data

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